A variety of drugs have been used in the past to aid as antihistaminic agents or as appetite stimulants, including those characterized as 1-alkyl-4-(5H-dibenzo[a,d]cyclohepten-5-yliden)-piperidines and the 10-keto or 10-hydroxy derivatives thereof.
Prior to the present invention, it was known that the compound cyproheptadine of the structure ##STR1## and the 10-keto or 10-hydroxy derivative were active antihistaminic and/or antiserotonin agents and were therefore useful in the treatment or relief of certain allergic conditions. This is disclosed in U.S. Pat. No. 3,014,911, Edward L. Engelhardt, which patent was issued Dec. 26, 1961, and in John D. Prugh Canadian Pat. No. 912,553, which was issued Oct. 17, 1972.
The 10-oxo or -hydroxy compounds of the prior art are also known to possess enhanced antihistaminic activity and appetite stimulant properties relative to the 10-unsubstituted compounds. This is disclosed in Canadian Pat. No. 912,553 mentioned above.